Strike the rock, and water will come out of it for the people to drink. - Exodus 17:6

Storage Tank

The team recommends that a storage tank be installed in the distribution system.  The water tank serves two main purposes.  First, the tank acts as a storage unit which will fill up during the night when water demand is low and allow a for higher flow rates during the day.  The second purpose of the tank is to set a constant water pressure in the dormitory by resetting the hydraulic grade line to that of the water elevation in the tank.  While four plastic tanks could be used, the team recommends that a ferrocement water tank be constructed.  Ferrocement tanks are more durable, easier to clean, and easier to repair than their plastic counterparts.  The ferrocement tank is to be a cylindrical tank 6.5 feet in diameter and 5.5 feet tall.  The metal structure will be made up of a ¼ inch rebar grid covered in two layers of chicken wire and 4 layers of ferrocement, see Figure 14. 

Ferrocement Tank


The tank will have an inflow line, an outflow line, a drain line and an overflow line. The tank was designed through hand calculations. 

From analyzing the spring, it was estimated to produce around 2900 liters of water per day.  The water demands of the dormitory were calculated to be about 3400 liters per day based on it lodging 40 kids.  Although this demand exceeds the supply, it was determined that it would be acceptable.  The kids will only stay in the dormitory Monday through Thursday, and then they will return to their homes on the weekends.  The water demand for the 3 days over the weekend will be minimal since all the children are at home.  A tank size of 5000 liters was determined to allow for additional volume to accumulate during the weekend and allow for large demand fluctuations.


The tank’s required elevation was determined by calculating the elevation that would give a static hydraulic pressure of 40 psi at the dormitory (a typical household pressure).  This elevation was found to be 28 meters above the dormitory, or an elevation of 2028 meters above sea level. 
The tank will be located 600 meters northeast of the dormitory as can be seen in the following figure.

New Tank Location